Sifter system



Sept. 28, 1937. I M. J. WATSON 2,094,433

SIF'IER SYSTEM Filed Nov. 22, 1935' 2 Sheets-Sheet 1 Fig.1.

Inventor M. J. WATSON Sept. 28, 1937.

SIFTER SYSTEM Filed Nov. 22, 1935 2 Sheets-Sheet 2 111 we ntor a /Mm//%/)7. 3

Patented Sept. 28, 1937 UNITED STATES PATENT OFFICE SIFTER SYSTEM MyronJ. Watson, Chicago, Ill. Application November 22, 1935, Serial No.51,045

4 Claims.

This invention relates to certain new and useful improvements insiftersystems, the peculiarities of which will be hereinafter fullydescribed and claimed.

My. present invention relates to that class of sifter systems in whichfinely pulverized material, such as grain, rock, mineral or othermaterial, is finely pulverized in a suitable machine and then deliveredto my system under compressed f as air currents in which the material isheld in suspension, and by my construction of sifter system is preventedfromclogging or undesired deposit within the. system, so that saidmaterial: is continuallyinmotion and divided by the sifter deviceintothe'desired grades of fineness, some of which grades aredrawn off atdefinite points of the system, while the balance containing the finestparticles of .materialis finally separated from the blast air and drawnoff in its finished condition as a finally finely pulverized product.

Witli the:above objects in view, my system comprises a casing of-aninverted conical shape inwhich is mounted. a conical screen havingopenings of the desired fineness, and a corresponding conical rotaryframe carrying brushes which engage the inner :side of'the screen and bytheir continual rotary contact, prevent clogging of theopenings in thescreen, and maintain the particles of the material constantly'in motionin thevehicular blast. air currents passing through thepreliminarysifter to the final cyclone collector in which latter the compressed airis separated from the finest particles, while said particles are drawnoil as finished product.

. Another object is to provide such construction of the sifter that theframe and'brushes, and the screen itself, are easily accessible so thatthey can be readily removed for change or replacement as V desired.

Another object is the provision of a safety device by which'the pressureof a possible explosion within said chamber maybe relieved and avoid,

rupture of the system. H 7 V Another object is to rotate said brushes bythe force of the entering blast air.

f Another object is tocontrol the speed of rotatio'nof the saidbrushes'by means operated by the entering blast airfand to increase orlessen the rotative speed as may be desired.

.Another object is to provide means for keeping the pulverized materialin suspension by agitating: and deflecting the entering blastair bearing7 said material, to avoid its clogging the screen and its tendency tolodge within the Sifter.

sectional plane 2--'2, Fig. 1, showing deflecting 7 blades and asupporting frame therefor;

Fig. 3, a vertical section on the line 3-3, Fig.

2, showing a brush mechanism operated by fan blades in :the path of theentering blast air;

Fig. i, a plan view of a cyclone collector on a sectional plane 44, Fig.1; and

Fig. 5, a sectional elevation of said cyclone collector on the line 5-5of Fig. 4.

Referring to the drawings, the numeral I designates a pulverizer ofsuitable type for pulverizing grain, rock, mineral or other material..Such pulverized material. is delivered by a pipe 2 to a blast fan 3which isconnected by a pipe 4 to an upright casing 5"having acylindrical top 6 and a conical bottom portion 1. The cylindricalportion. has a top 8 which is detachably, mounted thereon and held byset screws or otherwise but may be readily removed to give access to theinterior of the casing and remove the operating devices now to bedescribed. r

In the conical part of this casing is mounted a conical screen 9 havinga. packingring ill at the top so that the blast air. with its pulverizedmaterial will be delivered tothe inside of the screen. The fines thatpass through the screen are delivered by a downwardly inclined pipe H toa suitable collector such as a cyclone collector W to separate the airfrom the fines'which latter are discharged from the bottom of thecyclone into .a. bag or otherreceptacle; while the air, freed of thefines, escapes through the center outletl3. T

The coarse particles of the pulverized material which 'donot passthrough the screen 9, are delivered as tailings through a pipe Mconnected .to the bottom of said screen and passing out through saidpipe H and ending in asacking spout or other valve device i5 whichprevents the escape of the tailings until opened for their discharge. IIn the central axis of said screen is mounte a rod or shaft I6 in abearing at the top and bottom. This shaft is freely rotatable and has anadjusting screw I! at the lower bearing or is sired. On this shaft ismounted a conical frame connected at the top by radiating arms to theshaft and carrying brushes IS on the inclined portions of said frame,which brushes are substantially in contact with the inner face of saidscreen 9. The brushes may be adjusted by said adjusting screw to varytheir contact with the screen, or by any other suitable means. As thesebrushes rotate, by means presently to be described, they keep theopenings in the screen clear for the passage of fines which pass throughthe pipe H to said cyclone or other collector.

In the cylindrical chamber above the conical portion, is mounted aseries of radiating frames 19 carried by said shaft I6 as shown in Figs.2 and 3. In said frames are pivotally mounted defiecting blades 20'which are varied in their inclination by rotation on their horizontalaxes by suitable adjusting means, such as a vertical handle 2i having apinion and bevelled gear connection with the axis of each blade. Accessis had to adjust the inclination of these blades through a cappedopening 22.

Rotation is effected by the impact of the material carrying blast airentering the casing and impinging upon said blades as a fan, whichcauses rotation of the shaft 16 and the conical frame and brushes alsocarried by said shaft.

While these blades deflect the blast air downward like a fan, they aremotivated by the impact of the entering air currents, similar to turbineblades actuated by water impact. The brush-carrying shaft being freelyrotatable and having such turbine fan mounted thereon, is thereforedriven by the said blades. Also the speed of rotation is varied byadjustment of the inclination of these fan blades, which is a functionnot possessed by fixed turbine blades.

When said blades are vertically disposed, the velocity of the fan and ofthe brushes will be{ greater than when said blades are inclined more orless to the horizontal. When the blades. are inclined, the pulverizedmaterial in the entering blast air is deflected downward into theconical screen where such material is agitated by the brush frame as itseeks outlet through the screen. The radiating arms IQ of the fan framelikewise agitate the material in suspension as the said frame is rotatedunder the impulse of the entering air as just described.

Thus any tendency of the pulverized material to lodge or clog the screenor other part of the sifter .cone, is practically avoided, and at thesame time the said particles are so agitated and kept in suspension,that the fines quickly and readily find exit through the screen openingsinto the casing and are forced onward into said collector by thepressure of the blast air.

The screen is provided with hooks 23, and the top 8 of said casing whenremoved therefrom, allows of drawing up the screen by passing a liftingrope under said hooks, when the screen. is to be changed to another ofdifferent fineness as may be required for the material being sifted.

Likewise the shaft I6 carrying the fan and the conical frame with thebrushes, may also be drawn up from the lower bearing in which the shaftis mounted.

The casing I2 is provided with glazed openings 24 at different heights,by which theoperation of the brushes may be viewed from outside andadjustment made accordingly. The usual clean out opening 25 near thebottom of .:the casing gives access, for adjustment of the shaftcarryotherwise adapted to be raised or lowered as deing the brushes whendesired to make closer or lesser contact of the samewith the conicalscreen.

Thus it will be seen that the rotation of the brushes is effected bymeans entirely within the casing, and not operated by outsideconnections; also that the speed of rotation can be controlled byadjusting the inclination of the fan blades to the entering blast air;also that the fan frame and the brush frame cooperate in agitating theair and keeping the pulverized material in suspension so that the fineswill be readily passed through the screen and onward to the collector,while the tailings are discharged through the valvular device 15 beforementioned.

As the fines enter the cyclone collector tangentially under thecontinued impulse of the blast air, the centrifugal motion in the upperpart of the cyclone increases as the material descends the conical lowerportion, and causes a vortex in the center and an upward motion of theair to the discharge opening it connected to the tubular 25 dependingfrom the top of the cyclone.

The velocity of the particle-laden air entering the large upper portionof the cyclone collector is substantially unchanged when the air-carriedparticles change from their straight tangential entering direction to acircular movement by which a centrifugal action is exerted on theparticles causing them to hug the inner wall of the collector chamber.As the diameter of this downwardly tapering cone decreases, the velocityremains substantially uniform, but the rotary motion increases, andlikewise the centrifugal tendency while the particles spiral downward,causing practical separation of the pulverized material from itsvehicular air and condensation of the latter which seeks exit throughthe small bottom outlet and upward through the tubular 26 to the saiddischarged opening [3.

The lightest particles are not so readily separated by centrifugalaction from the whirling air currents as the larger particles, and arethus liable to be carried out the upper discharge opening with thepurified air unless the diameter of the tubular bears a certain definiterelation to the condensed air pressure which would avoid such loss. Inthe usual more or less approximation to this perfect proportion, many ofthese lightest particles would escape through the air discharge opening26 if it were not for a collecting device that I have provided by whichmost of these lightest particles are taken. out of the whirling aircurrents at or near the point of greatest compression near the bottomoutlet of the cone, and are returned by a communicating pipe to a pointin the upper part of the cyclonecollector where they will again minglewith the particle-laden air entering the tangential inlet. The airpressure is also distributed by this return pipe,'such as through avertical pipe 21. This pipe is mounted in the axis of the cyclone andits lower end hangs adjacent to the lower discharge opening. The upperportion of said pipe passes outside the tubular and is curved in thedirection of the material laden air entering the cyclone as shownin Fig.4. Thus the air passing upward through said pipe and outward through thecurved end adjacent to the cyclone inlet, merges the air currents fromsaid pipe with the entering blast air under the force of the airpressurein the lower portion of the cyclone collector. 7

Referring again to the sifter casing, the opening 22 has its cap 22detachably mounted so as to serve as a safety. cap and relieve thepressure within the casing, in the event of an explosion of the dusttherein.

I claim:

1. A sifter system comprising an upright casing having a conical bottomand a top forming an upper chamber with a tangential inlet subject tomixed feed of blast air and pulverized material in suspension, avertical freely rotatable shaft mounted in the axis of said casing,radiating frames supported by said shaft, adjustable fan bladespivotally mounted in said frames in the path of the entering mixed feedblast acting to drive said shaft and inclined so as to deflect saidblast downwardly into said conical bottom, means to Vary adjustably theinclination of said blades, a conical frame carrying brushes operablyconnected to said fan blade frames, a conical screen mounted in saidconical bottom subjected to rotary downward currents of material insuspension, and outlet pipes forthe fines and tails from said screen,substantially as described.

2. A sifter system as in the last claim, the means for adjusting thefanblades consisting of a vertical handle having a pinion and bevel gearconnection with each blade. 7 I

3. A sifter system comprising an upright casing having a lower portion,and a top portion forming a cylindrical chamber with a tangential inletfor material-laden air currents, a screen in said lower portion, afreely rotatable shaft in the axis of said casing, brushes adjacent saidscreen and carried by said shaft, and driving means for said shaftcharacterized by a set of inclined radiating blades mounted in saidchamber on said shaft in the path of the entering air currents anddriven thereby, and acting to deflect said currents downwardly into saidlower portion and against said screen, and outlet pipes for coarse andfiner particles.

4. A sifter system comprising an upright casing having a cylindrical topportion with a tangential inlet subject to blast air currents containingpulverized material, a lower portion of said casing containing a screen,a freely rotatable shaft therein carrying screen-cleaning brushes, andprovided with outlets for coarse and finer particles, and said topportion containing combined shaft-driving and air-deflecting means, andagitating means for the material in suspension in said air currents,bothsaid means being actuated by the blast air currents entering by saidtangential inlet.

' MYRON J. WATSON.

